能谱CT容积碘含量在晚期胃癌化疗疗效评价中的价值

Value of dual-energy CT-based volumetric iodine-uptake in the evaluation of chemotherapy efficacy in advanced gastric cancer

目的探讨能谱CT容积碘含量(VIU)作为晚期胃癌化疗疗效评价标准的价值。方法纳入标准:(1)既往未经系统治疗;(2)化疗前后资料完整;(3)无化疗禁忌。排除标准:(1)化疗时间及次数未完成;(2)原发灶不可测量;(3)图像质量差,胃腔充盈欠佳。收集2017年2月至2018年2月期间,在温州医科大学附属第一医院经胃镜病理确诊、经影像学和临床评估需行化疗的52例晚期胃癌患者临床及影像学资料。其中男性38例,女性14例,中位年龄65(31~88)岁。所有患者在化疗前和第3个化疗疗程结束后均行能谱CT双期增强扫描,测量门静脉期化疗前后的参数值:病灶最大径(在横断面、冠状面及矢状面分别找到病灶最大层面后测量肿瘤长径,取三者中最大值为肿瘤最大径)、病灶平均CT值(在病灶最大横断位层面手动画取感兴趣区,避开肿瘤边缘约2mm,测量CT值)以及VIU(病灶体积×碘浓度IC值),并计算化疗前后病灶最大径、VIU和平均CT值变化率[(化疗后指标-化疗前指标)/化疗前指标];分别以RECIST1.1(化疗后病灶最大径变化)、Choi(化疗后病灶平均CT值变化)及VIU(化疗后病灶VIU变化)评价标准评估化疗后疗效,包括完全缓解(CR)、部分缓解(PR)、疾病稳定(SD)和疾病进展(PD);CR、PR和SD归为有效组,PD归为无效组。采用配对t检验或Wilcoxon符号秩检验比较化疗前后参数值的变化,并采用Spearman相关分析和Kappa检验对3种疗效评价标准的疗效评估结果进行相关性分析和一致性检验(Kappa值≥0.75,说明一致性较好)。结果52例晚期胃癌患者化疗前后病灶参数值的比较,化疗后患者平均CT值[(74.01±16.75)HU比(81.06±15.87)HU,t=2.202,P=0.030]及VIU[中位数668.53×102μg比272.52×102μg,Z=4.761,P<0.001]均明显低于治疗前,差异均有统计学意义;而病灶最大径的差异无统计学意义[(66.71±34.49)mm比(78.45±35.62)mm,t=1.708,P=0.091]。VIU变化率中位数为-53.33%明显大于CT值变化率的中位数-5.75%,差异有统计学意义(Z=-5.408,P<0.001)。根据RECIST1.1标准,提示有效组47例(90.4%,包括PR19例、SD28例),无效组5例(9.6%);根据Choi标准提示,有效组45例(86.5%,包括PR37例、SD8例),无效组7例(13.5%);VIU标准提示有效组46例(88.5%,包括PR41例、SD5例),无效组6例(11.5%);将三者评价疗效的结果进行比较,差异没有统计学意义(χ2=0.377,P=0.828);经Choi及VIU评估为PR的比例明显高于RECIST1.1,评估为SD的比例明显较低(χ2值分别是16.861和24.089,均P<0.001),VIU及Choi两者评价PR和SD结果差异无统计学意义(χ2=0.887,P=0.346)。一致性及相关性分析显示,Choi和VIU评价疗效结果一致性及相关性最高(Kappa=0.912,P<0.001;r=0.916,P<0.001)。结论VIU对晚期胃癌化疗疗效评价具有一定的可行性,可能比依靠病灶最大径或CT值变化来评估的标准更灵敏。

Objective To explore the value of dual-energy CT-based volumetric iodine-uptake (VIU) in the evaluation of chemotherapy efficacy in advanced gastric cancer. Methods Inclusion criteria of subjects:(1) without previous systematic therapy;(2) with complete clinical information before and after chemotherapy;(3) without contraindications of chemotherapy. Exclusion criteria of subjects:(1) unfinished duration and times of chemotherapy;(2) unmeasurable primary lesions;(3) poor imaging quality or poor gastric filling. Clinical and image data of 52 patients with advanced gastric cancer who were diagnosed by pathology from gastroscopic biopsy, and needed chemotherapy evaluated by imaging and clinical information in the First Affiliated Hospital of Wenzhou Medical University from February 2017 to February 2018 were collected and analyzed. Of 52 patients, 38 were male and 14 were female with the median age of 65 (31-88) years old. All the patients underwent a dual-energy, dual phase-enhanced CT scanning before chemotherapy and after the third chemotherapy session. The parameters of the lesions measured before and after chemotherapy in portal vein phase were as follows: the maximum diameter (the largest diameter among those measured in the cross-sectional, coronal, and sagittal planes), average CT value (the regions of interest were manually pinpointed under cross-sectional planes with largest diameter of the tumor, which did not include regions less than 2 mm to the edge of the tumor) and VIU (lesion volume × iodine concentration). The change rates of maximum lesion diameter, average CT value and VIU before and after chemotherapy were calculated [(post-chemotherapy parameters-pre-chemotherapy parameters)/ pre-chemotherapy parameters]. The efficacy of chemotherapy was evaluated by RECIST 1.1 (the change of maximum tumor diameter after chemotherapy), Choi (the change of average CT value after chemotherapy) and VIU (the change of VIU after chemotherapy), respectively, which was categorized by complete response (CR), partial response (PR), stable disease (SD) and progressive disease (PD). Patients with CR, PR, and SD were assigned to the effective group, while those with PD were classified as the ineffective group. Paired t - test or Wilcoxon signed ranks test was used to compare the changes of parameters before and after chemotherapy, whereas Spearman correlation analysis and Kappa test were used for the correlation analysis and the consistency test between the three evaluation criteria (Kappa≥0.75 indicated good consistency). Results After chemotherapy, the average CT value [(74.01±16.75) HU vs.(81.06±15.87) HU, t=2.202, P=0.030] and median VIU (668.53×102 μg vs. 272.52×102 μg, Z=4.761, P<0.001) decreased significantly, while the difference of the maximum diameter was not statistically significant [(66.71±34.49) mm vs.(78.45±35.62) mm, t=1.708, P=0.091]. The median change rate of VIU (–53.33%) was greater than that of CT values (–5.75%) with significant difference (Z=-5.408, P<0.001). According to the RECIST 1.1 criteria, 47 patients (90.4%, including 19 with PR and 28 with SD) were effective and 5 patients (9.6%) were ineffective. According to the Choi criteria, 45 patients (86.5%, including 37 with PR and 8 with SD) were effective and 7 patients (13.5%) were ineffective. According to the VIU criteria, 46 patients (88.5%, including 41 with PR and 5 with SD) were effective and 6 patients (11.5%) were ineffective. Efficacy comparison among these three criteria showed no significant difference (χ2=0.377, P=0.828). As compared to RECIST 1.1 evaluation, the proportion of PR evaluated by Choi and VIU was significantly higher (χ2=16.861, P<0.001), whereas the proportion of SD was significantly lower (χ2=24.089, P<0.001). There was no significant difference in the proportions of PR and SD between VIU and Choi criteria (χ2=0.887, P=0.346). Consistency and correlation analysis showed that the VIU and Choi evaluation criteria presented the highest consistency and correlation (Kappa=0.912, P<0.001;r=0.916, P<0.001). Conclusion VIU is a feasible parameter for the evaluation of chemotherapy efficacy in advanced gastric cancer, and may be more sensitive than the evaluation criteria based on maximum diameter or change of CT value in the tumor.